This invention relates to new quinonediimine derivatives of triazine compounds which are useful as antiozonants for rubber, processes for their manufacture, and to their use in inhibiting the deteriorating effect of ozone on unsaturated polymers. In particular, novel N-alkyl-p-quinonediimino triazine compounds are described.
It is well known that ozone causes surface cracking of conventional highly unsaturated rubber vulcanizates when the rubber is placed under strain in an ozone environment. The most severe deterioration occurs when a small number of cracks are formed which grow rapidly into deep, disruptive fissures. These ozone cracks seriously shorten the serviceable life of the article.
The use of well known paraphenylenediamine materials has improved ozone protection under both static and dynamic conditions, however, even the best of the class have a very strong tendency to both stain and discolor. The term "stain" or "staining" is herein used to describe the characteristic of a material to diffuse through a polymeric substrate and discolor the adjacent surface. This diffusion staining is highly objectionable in most light colored rubber articles. In tires, which is the largest application in which the ozone protection is required, the tendency to diffusion staining of the aforementioned paraphenylenediamine materials is objectionable particularly in white sidewall type tires. Even in non-white sidewall type tires, the tendency of the materials to diffuse to the surface of the tire sidewall can be objectionable in that a brown or yellow dull surface is created on the tire sidewall. One common term for this phenomena is blooming. This is aesthetically objectionable in that it detracts from the general jet black, smooth appearance of a new tire. It is obvious that in a white sidewall tire, the migration of the brown or yellow discoloring material to the surface of the white sidewall is highly objectionable and generally difficult to remove during cleaning of the tire surface.
An object of this invention is to provide an antiozonant material which is highly effective in protecting the carcass from ozone attack. A further object is to provide ozone protection in a static condition at very low levels and to protect the rubber article during extended aging conditions against ozone attack. Yet another object is to produce a compound which does slowly diffuse and does not produce an objectionable brown or yellow bloom.
An advantage of the substituted triazine compounds is that it produces a substantially non-staining antiozonant of high molecular weight. A further advantage is that it slowly migrates to the surface of the rubber article. Another advantage is that the compounds do not tend to increase scorchiness of the compounded rubber stock in which it is used. This improves processing safety over other paraphenylenediamine antiozonants.